Cementing method allowing initial liner top pressure integrity confirmation

ABSTRACT

Cementing takes place after a hanger and seal are set to first insure the pressure integrity of the connection between the string to be cemented and the existing tubular. Cementing top down or bottom up is envisioned with either displaced fluid returning toward the surface in a crossover tool or with the displaced fluid squeezed into the formation. A work string manipulates the crossover for reversing out after cementing. For running in a valve assembly is held open to permit circulation. Work string manipulation allows at least one valve that keeps the cement in the annulus to close and at least one other valve to close that keeps the reverse fluid from leaving the cemented tubular to allow such flow to return to the crossover and out to the surface. Valve release can be done with a pressure responsive sleeve instead of a stinger on the running string.

FIELD OF THE INVENTION

The field of the invention is cementing and more specifically a methodallowing setting a liner hanger seal to determine pressure integrity ofthe connection before cementing bottom up or top down or with returns orby squeezing the formation.

BACKGROUND OF THE INVENTION

Typically in a cementing operation the tubular string being cemented ishung off an existing tubular with an anchor portion of a hanger whileleaving the seal unset so that the delivered cement can displace fluidaround the set anchor. When the cement is properly placed the hangerseal is set. However, the pressure integrity of the connection to theexisting tubular cannot be determined before the cement is pumped. Thedisplaced fluid that flows past the hanger seal can have debrisincluding particles of the cement that would later foul the seal areathus preventing an adequate seal. In some instances when this happensanother seal can be run in and set above the seal that did not properlyseal off pressure. This is an expensive and time consuming process. Itis more advantageous to be able to determine the integrity of theconnection before cementing begins and one of the objectives of thepresent invention is to provide equipment that facilitates a method toaccomplish this goal.

Many times when a cement job is done in a top to bottom direction thedisplaced fluid is simply pushed into the formation. This is calledsqueeze cementing and is commonly done because typical cement shoes,which are the one way valve assemblies at the bottom of a string beingcemented allow cement out of the string in a conventional cement job(bottom up) but block return flow. If doing a top down cement job astandard shoe would block displaced fluid trying to come back into thestring. As a result top down cementing is done with squeezing displacedfluid into the formation. Squeezing the formation can adversely affectsubsequent production.

ON THE TECHNICAL SOLUTION

The method of the present invention allows for fluid displacement into awork string during cementing as well as preventing fluid from thesurface coming down the work string from getting out of the tubularstring lower end to facilitate a reversing out of excess cement after acement job.

With the equipment provided, a cement job can be run in the standard wayof bottom up or it can be done in a reverse direction of top down whiletaking displaced fluid or with a squeeze configuration, all with theliner hanger seal already set so that the pressure integrity of theconnection to the existing tubular can be confirmed before cement ispumped.

This flexibility is provided with a sub that has a stack of valves,preferably full opening flappers. One or more lowermost valves are heldopen when running in with a stinger connected to a running string or apressure actuated sleeve. At least one uppermost valve is initially heldopen for running in but when released to operate prevents cement flowinto the tubular string. The lowermost flappers permit displaced fluidinto the tubular string when pumping cement top down and hold against areversing out fluid stream coming down the liner to remove excesscement. A cement crossover allows the cement to exit to the annulus nearthe top of the string and below the tubular hanger and seal. Isolatorsare provided for the running string that can be dart activated as abackup to close the return path from the crossover in the event theflappers are not properly released. In the alternative with no innerstring extending to the flappers a packer is alternatively provided onthe stinger assembly for the flappers that can be dart actuated to closeoff the liner in an emergency if the flappers fail to actuate.

These and other aspects of the present invention will become morereadily apparent from a review of the description of the preferredembodiment and the associated drawings while recognizing that the fullscope of the invention can be determined from the appended claims.

SHORT SUMMARY OF THE INVENTION

The invention is a well completion method for supporting and cementing atubular string from an existing tubular and a well liner cementingassembly comprising More specific, the invention is a petroleum wellcompletion method for supporting and cementing a tubular string from anexisting tubular comprising running in, on a running string, saidtubular string with a hanger and seal assembly to position said hangerand seal assembly by the desired location on the existing tubular,setting the hanger and seal, pressure testing the integrity of theconnection between the string and the existing tubular after saidsetting, then after said setting and said pressure testing, cementingsaid tubular string .

The invention is also a petroleum well liner cementing assemblycomprising a drill pipe string with a tubular string release toolarranged for holding a liner hanger setting sleeve of a liner stringsaid liner string provided with a liner hanger and seal assembly, saidliner string provided with an annulus cementing port operated by acrossover tool assembly arranged on said drill pipe string below saidtubular string release tool, said liner string provided with lovervalves held open during running in by a cementing stinger arranged belowsaid crossover tool assembly, and said seal assembly allowing pressuretesting when said liner hanger is set in a casing.

Cementing takes place after a hanger and seal are set to first insurethe pressure integrity of the connection between the string to becemented and the existing tubular. Cementing top down or bottom up isenvisioned with either displaced fluid returning toward the surface in acrossover tool or with the displaced fluid squeezed into the formation.A work string manipulates the crossover for reversing out aftercementing. For running in a valve assembly is held open to permitcirculation. Work string manipulation allows at least one valve thatkeeps the cement in the annulus to close and at least one other valve toclose that keeps the reverse fluid from leaving the cemented tubular toallow such flow to return to the crossover and out to the surface. Valverelease can be done with a pressure responsive sleeve instead of astinger on the running string.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached figures illustrate some embodiments of the claimedinvention.

FIG. 0 is a simplified sketch illustrating a well bore with a wellhead,casing, with casing shoe, extending from the sea bed surface, a tubularstring (35) and a running string (43).

FIGS. 1a-1e is a combined partial elevation view and partial sectionview of a liner string and a tool string. The figure show the flowscheme for fluid circulation when running in with an inner stringstinger (100) at a lower end.

FIGS. 2a-2c is a combined partial elevation view and partial sectionview of a liner string and a tool string and showing the inner stringlifted for the cementing position with flappers released that allowdisplaced fluid into the string from the annulus being cemented.

FIGS. 3a-3c are the same as 2 a-2 c with the flow direction reversedafter release of a valve to hold fluid in the string to allow forremoval of excess cement.

FIG. 4 is a detailed combined partial elevation view and partial sectionview of the valve assembly when circulating during miming in and with nostinger in the work string.

FIG. 5 is the view of FIG. 4 during cementing with the two lowerflappers (2) released to operate.

FIG. 6 is the view of FIG. 5 with the top flapper (1) released tooperate.

FIG. 7 is the view of FIG. 6 showing the reverse out flow for removingexcess cement.

FIG. 8 shows the stinger variation holding valves open to allowcirculation when running in.

FIGS. 9 and 10 show the stinger lifted to allow the lower two flappers(2) to operate with a top down cementing flow.

FIGS. 11 and 12 are the view of FIGS. 9 and 10 with the top flapperreleased to accommodate reversing out excess cement.

DESCRIPTION OF OF THE INVENTION

The invention will in the following be described and embodiments of theinvention will be explained with reference to the accompanying drawings.

Before a detailed discussion of the components that facilitate themethod are discussed, a general review of the method will serve as anintroduction.

A tubular string to be cemented is delivered through an existing stringso that a hanger/seal of the string to be cemented is positioned nearthe lower end of the existing tubular. Unlike prior cementing methods,both the anchor and the seal are actuated from the string to be cementedagainst the existing string so that the pressure integrity of theconnection is tested before cementing begins. During running in forproper position of the hanger/seal, also commonly referred to as a linerhanger when the string to be hung and sealed is a liner string,circulation is enabled through a lower valve sub as the valves are allopen. References hereafter to “liner hanger” are intended to includestructures that support and seal a liner or a casing string. Return flowcomes up the annulus outside the string being run in. After the linerhanger is fully deployed and the pressure integrity test is completed,the cementing can begin. The work string is released from the now setliner hanger and raised up to pull a stinger from at least one flapperthat opens when displaced fluids from the annulus in a top downcementing operation are pushed into the tubular string. After the cementis placed another flapper is released that prevents cement from leavingthe annulus and flowing into the string just cemented. The flowdirection is reversed from the cementing step through a crossover wherethe flow is now inside the string but around the running string. Theinitial flapper that was allowed to operate when picking up now blocksthe flow within the string and around the running string forcing theflow with the excess cement back up through the running string and tothe surface through the crossover. The inner string is then removed andthe top down cementing job done with taking displaced fluid returnstoward the surface is complete. As an alternative to releasing thevalves in the valve sub to be functional using a stinger lifted out ofthem as described above, another way is to use pressure sensitivesleeves that shear at different pressures to first release the valve orvalves that allow displaced returns into the string being cemented andfollowing the cement placement in a top down direction to releaseanother valve that keeps fluid from leaving the tubular so that areversing out of excess cement can be accomplished. In this variation abackup is made available if the flappers fail to close to hold thecement in the annulus by closing off inside the string using a dartdropped in a bushing. After the cement sets the inside of the string canbe milled to remove any cement with up to the bushing.

With the above as an introduction the assembly with the removablestinger 100 extends from connection 16 in FIG. 1e down to debris sub andsleeve catcher 4 at a lower end. In between are a quick connect coupling11, 12; a no go and shear up locator 7 and a float valve 8. For runningin, the stinger 100 holds open the shear flapper valve 1, alsoconsidered the second flapper valve, and the reverse flapper valves 2,also considered the first flapper valve, of which there are twoillustrated with one to back up the other. The shear flapper valve 1prevents flow into the guide shoe 6 from the annulus 102 when the cementis delivered there, preferably from a top down direction. The reverseflapper valves 2 allow fluid displaced by the delivered cement to passinto the shoe 6 and the debris baffle plate 5. Holes 104 are sealed offby seal 9 in the running in position. Flow into the stinger 100 duringrunning in is represented by arrows 106 with arrows 108 representingreturn flow in annulus 102 toward the surface as will be explained belowwith regard to FIGS. 1a-1d showing the remainder of the assembly aboveFIG. 1 e.

Referring to FIG. 1a shows the running string 43 supporting the tubularstring release tool 42 in suspending the liner hanger 38 that has a seal39. Tool 42 is connected to liner hanger setting sleeve 40 in areleasable manner. In FIG. 1b the packoff bushing 37 is fitted intopolished bore receptacle 36 to close off annular space 110 to directcirculation flow along the path delineated by arrows 106 and 108. Theliner or casing is 35 and the cement ports are 34. Items 32 and 33collets used in location of the crossover tool assembly 25-29 shown inFIG. 1c for cement delivery out ports 34. Expansion joints 30 can alsobe used adjacent the crossover tool assembly 25-29. The crossover toolassembly 25-29 continues to connection 18 in FIG. 1d and includesstandard features such as a ball seat 19, a back flow check valve 20, ashroud for a dart catcher 21 and a dart catcher with no flow through 22.

As seen in FIG. 1 the circulation flow down is reflected by arrows 106is forced through the crossover tool assembly 25-29 down past connection18 and through the stinger 100 with holes 104 isolated until an exitthrough the guide shoe 6 followed by return to the surface as indicatedby arrows 108 around the outside of the liner or casing string 35.

When the liner hanger 38 is properly located, its anchor assembly andseal 39 are set with sleeve 40 and the running tool 42 can release. Apressure integrity test can be run on the seal 39. The running string ispicked up as shown in FIGS. 2a-2c . Doing so lifts the bushing 37 out ofthe polished bore receptacle 36 as also shown in FIG. 2a . It alsoaligns the crossover assembly 25-29 with the cement ports 34 as shown inFIG. 2b . Ports 104 in stinger 100 are now open and the stinger has comefull out of the reverse flapper valves 2 and the shear flapper valve 1.However, sleeve 112 is still holding shear flapper valve 1 open in FIG.2c . As a result when cement is pumped down the running string 43 asindicated by arrows 113, the flow crosses over in FIG. 2b to outside thestring 35 at ports 34 and continues down the annulus 102 into guide shoe6 that can have uniquely configured flow ports to accommodate thecement. Ahead of the cement flow represented by arrows 113 fluid isdisplaced as indicated by arrows 114 through the valves 1 and 2, withvalve 1 held open at this stage and valves 2 being pushed open by thedisplaced fluid. Valves 2 allow one way flow into guide shoe 6 but stopflow in the direction for getting out of the string 35 through guideshoe 6.

When the cement is delivered to the annulus 102, pressure is built up toput a force on sleeve 112 to break a shear pin that is not shown thatwill then allow the sleeve 112 to shift downward away from flapper 1 torelease it to operate. Flapper 1 is oriented to prevent flow into string35 but opens when reversing out the excess cement as shown in FIG. 3.However, valves 2 are operational to cause the flow direction to reversefrom incoming flow indicated by arrows 116 to return flow indicated byarrows 118 as the reverse flow passes through holes 104. The top downcementing done after setting a liner hanger seal and pressure testingthe connection to the existing tubular is now complete. The top downcementing occurs with displaced fluid going toward the surface throughthe crossover as illustrated but the operation can also be done as asqueeze into the formation if the return path through the crossover isclosed off.

There is an alternative way to operate the flappers 1 and 2 without thestinger 100. In FIG. 4 sleeve 3 holds open flappers 2 for running inwith holes 120 sealed off so that circulation flow for running inindicated by arrow 122 passes through the sleeve 3 as well as flappers 1and 2 and then through guide shoe 6 and back to the surface in theannulus 102 through the crossover assembly that is not shown in FIG. 4.As before sleeve 112 keeps flapper 1 open during running in. In FIG. 5sleeve 3 is shifted with applied pressure to release valves 2 to operatein the manner described before. Cement comes top down as indicated byarrows 124 displacing well fluid through holes 120 and valves 1 and 2.Valves 2 are pushed open by the displaced fluid while valve 1 is stillheld open. Returning flow represented by arrows 126 goes to the surfacethrough the crossover assembly that is not shown in FIG. 5. In FIG. 6applied pressure has put a force on sleeve 112 to allow valve 1 thefreedom to operate to keep cement from leaving the surrounding annulus102. Once valve 1 is operational, reverse flow represented by arrow 128comes down and opens valve 1 but is stopped by valves 2 and returnsuphole to the surface through the crossover. In this embodiment seal 37′can be used in addition to seal 37 but in a lower location as shown inFIG. 1e with the idea that if valve 1 fails the cement can be retainedin the annulus 102 dropping a dart into seal 37′ while that seal ispositioned in a respective polished bore receptacle or is otherwise insealing contact with the string 35.

FIG. 8 shows an enlarged view of the stinger 100 running through thevalves 1 and 2 for running in to allow circulation out through guideshoe 6 and back to the surface as illustrated with arrows 130. FIGS. 9and 10 shows valves 2 operative after the stinger 100 is raised andarrows 132 being the top down cementing while well fluids are displacedahead of the cement as indicated by arrows 134. FIGS. 11 and 12 show thevalve 1 operative after cementing due to sleeve 112 movement so thatcement is prevented from u-tubing back into the string 35. The reverseout flow indicated by arrow 136 can push valve 1 open but valves 2 blockflow in the direction out of string 35 so that the excess cement canflow through the crossover that is not shown and toward the surface forremoval.

Those skilled in the art will appreciate that while flappers are shownfor valves 1 and 2 that other types of valves are contemplated that canbe selectively operated with ways other than string manipulation orapplying pressure to create a net force to move a sleeve. Valves 1 and 2can have redundant backup or not as deemed necessary by the operator orby cost considerations. The term “cement” is intended to include any andall known sealing materials. Some of the components have just beenmentioned with regard to their function such as the crossover tool orvarious collet systems used for its positioning. These components havebeen generally described because they are components well known to thoseskilled in the art. The position, placement and operation of the valvessuch as flappers 1 and 2 and how they are integrated into the describedmethod is the actual focus of the claimed method.

The system allows the liner hanger and its seal to be set so that thepressure integrity of the connection to the existing tubular can bedetermined ahead of the start of cementing. Cementing can then be donetop down with fluid displaced towards the surface or squeezed into theformation. A standard cement job from bottom up can also be undertaken.

The above description is illustrative of the preferred embodiment andmany modifications may be made by those skilled in the art withoutdeparting from the invention whose scope is to be determined from theliteral and equivalent scope of the claims below

1. A well completion method for supporting and cementing a tubularstring from an existing tubular, said method comprising the steps of:running in, on a running string, said tubular string with a hanger andseal assembly to position said hanger and seal assembly by the desiredlocation on the existing tubular; setting the hanger and seal; pressuretesting the integrity of the connection between the string and theexisting tubular after said setting; and cementing said tubular stringafter said setting and said pressure testing.
 2. The method of claim 1,further comprising the step of: performing said cementing of saidtubular string top down.
 3. The method of claim 2, further comprisingthe step of: allowing fluid displaced by said cementing into the tubularstring.
 4. The method of claim 2, further comprising the step of:squeezing fluid displaced by said cementing of said tubular string intoa surrounding geological formation.
 5. The method of claim 1, furthercomprising the step of: performing said cementing of said tubular stringbottom up.
 6. The method of claim 1, further comprising the step of:circulating fluid through said tubular running string and said tubularstring when running in, through a plurality of open valves located neara lower end of the tubular string.
 7. The method of claim 6, furthercomprising the step of: initially holding open said valves forcirculating fluid.
 8. The method of claim 6, further comprising the stepof: providing at least one of said valves as a selectively operablefirst check valve allowing flow into said lower end of said tubularstring when operable and another of said valves as a selectivelyoperable second one way valve preventing flow into said tubular stringwhen operable.
 9. The method of claim 8, further comprising the step of:locating said second check valve closer to a surface location than saidfirst check valve.
 10. The method of claim 9, further comprising thestep of: making said first and second check valves flapper valves. 11.The method of claim 10, further comprising the steps of: holding saidfirst flapper valve open with a stinger connected to a running string;and allowing said flapper valve to operate by raising said stinger witha running string.
 12. The method of claim 10, further comprising thesteps of: holding said second flapper valve open with a second flappersliding sleeve and using applied pressure in the tubular string to shiftsaid second flapper sliding sleeve to enable said second flapper tooperate.
 13. The method of claim 10, further comprising the steps of:holding said second flapper open with a sliding sleeve; and usingapplied pressure in the tubular string to shift said sleeve to enablesaid another flapper valve associated with said sleeve to operate. 14.The method of claim 12, further comprising the step of: performing saidraising of said stinger after said fluid circulating and before saidreverse cementing circulation.
 15. The method of claim 14, furthercomprising the step of: performing shifting said sliding sleeve aftersaid cementing to enable said second flapper valve to keep cement in asurrounding annulus.
 16. The method of claim 15, further comprising thestep of: using said first flapper valve to redirect reversing flow insaid tubular string to take out excess cement.
 17. The method of claim16, further comprising the step of: using a crossover tool in saidrunning string; and directing reversing out excess cement flow tooutside said running string at said crossover tool and taking returnswith the excess cement through said crossover tool and out to a surfacelocation via an annular space between said running string and saidtubular string.
 18. The method of claim 17, further comprising the stepof: providing redundant first or second flapper valves.
 19. The methodof claim 12, further comprising the steps of: holding said first flappervalve open with a first flapper sliding sleeve; and using appliedpressure in the tubular string to shift said first flapper slidingsleeve to enable said first flapper valve to operate.
 20. The method ofclaim 19, further comprising the step of: moving said first flappersliding sleeve before said second flapper sliding sleeve.
 21. The methodof claim 20, further comprising the steps of: cementing after movingsaid first sliding sleeve; and using said first flapper valve when madeoperable by said moving said first flapper sliding sleeve to allow fluiddisplaced by cement to enter said tubular string.
 22. The method ofclaim 21, further comprising the steps of: moving said second flappervalve sliding sleeve after delivering the cement; and using said secondflapper valve made operable by moving said second flapper sliding sleeveto prevent cement in the annular space around said tubular string fromentering the tubular string.
 23. The method of claim 21, furthercomprising the steps of: deflecting open said second flapper valve withreverse flow into said tubular string from a surface location after saidcementing; and redirecting said reverse flow in said tubular string withsaid first flapper valve to remove excess cement toward a surfacelocation.
 24. The method of claim 19, further comprising the steps of:providing a selectively operable seal in an annular space between saidrunning string and said tubular string; and positioning said seal in asealing position and blocking said running string adjacent said seal toretain cement in the surrounding annulus should said second flappervalve fail to operate.
 25. A petroleum well liner cementing assemblycomprising: a drill pipe string with a tubular string release toolarranged for holding a liner hanger setting sleeve of a liner string;said liner string provided with a liner hanger and seal assembly; saidliner string provided with an annulus cementing port operated by acrossover tool assembly arranged on said drill pipe string below saidtubular string release tool; said liner string provided with lovervalves held open during running in by a cementing stinger arranged belowsaid crossover tool assembly; and said seal assembly allowing pressuretesting when said liner hanger is set in a casing.
 26. The linercementing assembly of claim 25, said crossover tool assembly arrangedfor shifting a cementing section's valve sleeve to open cementing portswhile said cementing stinger is shifted upwards out of said lovervalves, allowing reverse circulating in of cement from said cement portsto the liner annulus and back through said lower valves of said linerstring.
 27. The liner cementing assembly of claim 26, said valvesarranged for being shut after reverse circulating in of cement, so asfor allowing normal circulation washing out of excess cement within saidliner below said crossover tool having shut said cement ports.
 28. Theliner cementing assembly of claim 26, said running string arranged fornormal circulating down of cement above said crossover tool assembly.29. The liner cementing assembly of claim 27, the running stringarranged for reverse circulating down the running string's annuluswithin the existing tubing and set liner during excess cement wash-out.